Identification methods of common chemical fertilizers

The main results are as follows: 1. Urea is granular or crystalline in appearance, which is easy to absorb moisture, absorb water from the air and dissolve, and is easily soluble in water and ammonia. Put a piece of iron on the stove and put the urea particles on it. The urea melts and volatilizes quickly. At the same time, there is a little white smoke, and you can smell ammonia. The content of agricultural total nitrogen (based on dry basis) is 46.0%.

2. Ammonium sulfate is white or light-colored crystal, easy to absorb moisture, easy to dissolve in water, and the aqueous solution is acidic. When it is dissolved in water, it absorbs heat and releases ammonia when it acts with alkalis. When heated on the fire, it melts more slowly than urea, ammonium nitrate and ammonia chloride. It can also be identified by the reaction of barium chloride with ammonium sulfate in water to form a white precipitate. The content of agricultural ammonia (in terms of dry basis) is 21.0% for first-grade products and 20.8% for secondary products.

3. Ammonium nitrate is white or yellowish in appearance, easily soluble in water, absorbs a lot of heat and lowers the temperature of water, and has strong hygroscopicity and caking. A large amount of ammonium nitrate can be burned or even exploded by thermal decomposition, and white smoke is produced, and ammonia can be smelled. The content of agricultural total nitrogen (based on dry basis) is 34.4% Mel 34.6%.

4. Ammonium chloride is white or yellowish crystal, easy to dissolve in water, solubility increases significantly with the increase of temperature, strong hygroscopicity, easy to agglomerate, the aqueous solution is acidic. Put a small amount of ammonium chloride on the fire, you can smell a strong pungent smell, accompanied by white smoke, ammonium chloride will quickly melt and all disappear, in the melting process can be seen in the unmelted part of the yellow. The content of agricultural total nitrogen (based on dry basis) is 25%.

5. Ammonium bicarbonate for agriculture is white or grayish crystal, smells of ammonia, has strong hygroscopicity, is easily soluble in water, and the aqueous solution is weakly acidic. When identifying, you can rub a small number of samples with your fingers, and you can smell a strong smell of ammonia. The content of agricultural nitrogen is 17%.

6. The appearance of calcium superphosphate is dark gray, grayish white, light yellow and other loose powder, slightly sour taste, is a kind of acidic chemical fertilizer, sensitive to the effect of alkali, easy to lose fertilizer effect. Some of them can be dissolved in water, and the aqueous solution is acidic. In general, the hygroscopicity is small, such as hygroscopicity occurs when the air humidity reaches more than 80%, forming a hard lump. Grade A contains 20% effective phosphorus pentoxide, grade IV A 13%, and grade B 12%.

7. The appearance of calcium magnesium phosphate fertilizer is grayish white, grayish green or grayish black powder, the powder is very fine, in the sun, you can generally see the existence of crushed, vitreous objects, sparkling. Insoluble in water, not easy to lose, non-hygroscopic, non-toxic, non-corrosive, heated on the fire, no change can be seen, the melting point is about 135 degrees Celsius. The effective efficiency of special grade products is 20% phosphorus pentoxide, 40% calcium oxide and 12% magnesium oxide.

8. The appearance of compound fertilizer is grayish brown or grayish white granular. In some compound fertilizers, there are incomplete urea grain crystals, while in some compound fertilizers, whole urea crystals exist alone. With slight hygroscopicity, the particles of compound fertilizer are easy to crush after moisture absorption. It is non-toxic, tasteless and non-corrosive. the nitrogen fertilizer, potash fertilizer and some water-soluble phosphorus in compound fertilizer can dissolve in water. When heated on the fire, white smoke can be seen, and the smell of ammonia can be smelled, which cannot be completely melted.

9. Ammonia is an aqueous solution of ammonia dissolved in water. It is colorless, transparent or yellowish. It has a strong irritating odor and is toxic. The aqueous solution is weakly alkaline. The content of ammonia in agricultural ammonia is generally 15%.